1. Field of the Invention
The present invention relates to computer networks. More specifically, the present invention relates to a method and an apparatus for waking up a sleeping system which resides on a computer network.
2. Related Art
In recent years, a large number of systems have been brought to the marketplace bearing logos which indicate that the system meets an energy saving standard. An increasing number of these systems are being attached to computer networks to allow workgroups to utilize their services. These systems typically enter a sleep (or power-saving) state when they have not been used for a certain amount of time. In order to restore a sleeping system to a normal operating state, a packet can be sent to the system that contains a specific bit pattern that can “wake up” the system. This packet is commonly referred to as a “magic packet” or “wake-up packet,” and the technology as a whole is referred to as “Wake-on-LAN.”
Today's enterprise networks can easily contain thousands of systems that are distributed over hundreds of LANs (Local Area Networks). Since a system is usually not fully functional when it is in a sleep state, it is very desirable to have a technique that can wake-up any sleeping system in the network.
In a sleep state, a system can typically receive packets of lower-layer protocols, such as Ethernet, but cannot respond to ARP (Address Resolution Protocol) requests. Unfortunately, being able to respond to ARP packets is often necessary for receiving packets of upper-layer protocols, such as IP (Internet Protocol). Hence, the wake-up packet is generally sent using a lower-layer protocol, such as Ethernet, instead of using an upper-layer protocol, such as IP. Unfortunately, such lower-layer protocols can only be used for sending packets within a LAN.
Consequently, present techniques for waking up sleeping systems are only applicable within a LAN, and they typically cannot be used to wake up systems across enterprise networks that are usually large and contain multiple LANs.
Hence, what is needed is a method and an apparatus for waking up a sleeping system from a remote system that is located on a different LAN.